The female vaginal mucous surface is suitable for microorganisms such as bacteria, fungi, etc. to inhabit. The dominant bacteria inhabited on healthy vaginal mucous surface are large Gram-positive rods, usually called “vaginal normal flora”. Most of these large Gram-positive rods belong to the category of lactobacilli, and are mainly lactobacilli. They are capable of producing acids by metabolizing glycogen in vaginal mucous epithelial cells so as to maintain the vaginal acidity within a pH value range from 3.5 to 4.5, preferably from 3.8 to 4.1. The vaginal acidity plays a very important role in the health of female genital tract and in the resistance of infections caused by pathogenic bacteria. Once abnormal changes in the vaginal flora and acidity occur, the chance of vaginal infection caused by various pathogenic bacteria is greatly increased.
Many factors may disturb vaginal flora and vaginal acidity so as to reduce the capability of resisting infections caused by pathogenic bacteria in female vagina. Thereby, vaginal microbial diseases are common in women.
Among vaginal microbial diseases, Candidal vaginitis, bacterial vaginosis (BV), cytolytic vaginosis (CV), and atrophic vaginitis (AV) are most common. They are all associated with the pathological change in vaginal acidity. As reported in a document, if a patient has the symptoms such as vulvovaginal pruritus and vulvovaginal burning pain and a vaginal pH value of from 4.0 to 4.5, the patient is diagnosed to have a high probability of suffering from Candidal vaginitis[1], if a patient has the symptoms such as vulvovaginal pruritus and vulvovaginal burning pain and a vaginal pH value of 4.0 or below, the patient is diagnosed to have a high probability of suffering from cytolytic vaginosis[1]. The inventors found after researches that the vaginal pH is mostly 4.0 or below, in particular, 3.8 or below in cytolytic vaginitis, and the pH is mostly 4.5 below, in particular 4.1 below in Candidal vaginitis. Therefore, when the vaginal pH is 4.0 or below, the patient might suffer from either Candidal vaginitis or cytolytic vaginitis. If a patient has the discomforts such as vulvovaginal pruritus and fishy smell and a vaginal pH value of 4.5 or above, the patient is diagnosed to have a high probability of suffering from bacterial vaginosis[2]. The vaginal pH is also greater than 4.5 in atrophic vaginitis.
After researches, the inventors found out that Candidal vaginitis, in particular, recurrent refractory Candidal vaginitis, are mainly endogenous infection. In acidic microenvironment formed by acids produced by vaginal lactobacilli, fungi (represented by Candida) overgrow and produce toxin, and therefore cause vaginal inflammations. In fact, most of the vaginal floras in these patients are dominated by lactobacilli. The characteristic is especially prominent in the case of recurrent, refractory candidal vaginitis. The Candidal hyphae or spores could be found in the patient's vaginal secretion. The pH value of vaginal secretion is usually below 4.5 and even lower than 4.1. The clinical symptoms include vulvovaginal pruritus, vulvovaginal burning pain, urodynia, algopareunia, etc. The symptoms are usually most serious before menstruation and alleviated during and after menstruation. The current therapeutic methods include the administration of various antifungal agents or antibiotics such as ketoconazole, nystatin, etc.
Cytolytic vaginosis are also associated with the overgrowth of vaginal lactobacilli, the over-production of acids by vaginal lactobacilli, and the too low pH value in vagina. Large and long Gram-positive rods are observable in vaginal secretion, while Candidal hyphae or spores could not be found. Usually, the vaginal acidity of patient is over-high, and the pH value of vaginal secretion is below 4.0 in general. The clinical symptoms are similar to those of Candidal vaginitis, including vulvovaginal pruritus, vulvovaginal burning pain, urodynia, algopareunia, etc., which usually are most serious before menstruation and are obviously alleviated during and after menstruation, as periodic episode. Therapeutic methods mainly include the demibain with alkali solution of sodium bicarbonate to neutralize the high acidity of vaginal secretion, and the administration of antibiotics Augmentin (Amoxicillin+Clavulanic acid) to inhibit lactobacilli.
Bacterial vaginosis is associated with the decrease of vaginal lactobacilli and the reduction of vaginal acidity. The pH value in vagina is higher than 4.5, the overgrowth of many microorganisms including anaerobic bacteria, etc. causes “polymicrobial syndrome”. The clinical symptoms include discomforts such as vulvovaginal pruritus, fishy smell leucorrhea, etc. Atrophic vaginitis is associated with the decrease of vaginal lactobacilli and the reduction of vaginal acidity, and is generally characterized by discomforts such as vulvovaginal pruritus, vulvovaginal pain etc.
The current methods for treatment of above vaginal microbial diseases mainly relate to inhibiting or killing microbials, for example, Candidal vaginitis is treated by inhibiting and/or killing fungi with antifungal agents selected from fluconazol, nystatin, clotrimazole, etc. Cytolytic vaginosis is treated by killing lactobacilli with antibacterial agents Augmentin, etc. Bacterial vaginosis is treated by killing anaerobic bacteria with metronidazole, etc.
After years of research and clinical practice, the inventors of the present invention found that said antibacterial treatments inhibit or kill pathogenic bacteria whilst killing normal vaginal lactobacilli and disrupting vaginal acidity, resulting in the reduction of the natural vaginal resistance against infection, and then the enhancement of pathogenic bacteria colonization, and thereby causing recurrent infection or persistent infection. How to avoid the disruption of normal vaginal lactobacilli and acidity and protect the natural anti-infection barrier in vagina during the treatment of vaginal infections is an unsolved problem for a long time. It is also a common problem confronted by microbial killing or inhibiting methods for treating various vaginal infectious diseases.
In the patent application PCT/CN2006/000826, the inventors of the present invention had disclosed a composition comprising saccharides and benzoic acid and/or sodium salt thereof as active ingredients for modulating vaginal bacterial flora and vaginal acidity, wherein saccharides are capable of promoting lactobacilli, and benzoic acid and/or sodium salt thereof significantly inhibit lactobacilli when the vaginal acidity is over-high. The composition of that invention promotes the growth of vaginal lactobacilli and the acid production of lactobacilli when vagina lactobacilli are rare and the vaginal acidity is weak, and inhibits the acid production of lactobacilli when the vaginal acidity is over-high, and therefore returns the abnormal vaginal bacterial flora into the normal bacterial flora dominated by lactobacilli and maintains the vaginal acidity within the range from 3.5 to 4.5, preferably from 3.8 to 4.1. The composition comprising anti-fungal agents mentioned therein is applied to the treatment of Candidal vaginitis. However, it is not mentioned that benzoic acid and/or sodium salt thereof itself has a preventive or therapeutic effect on Candidal vaginitis. Moreover, it is not mentioned that low content of benzoic acid and/or sodium salt thereof in combination with organic acid preservatives such as low content of dehydroacetic acid and/or sodium salt thereof, and/or low content of propionic acid and/or sodium salt thereof, and/or low content of sorbic acid and/or sodium salt thereof, etc. has a synergistic effect on the inhibition of vaginal fungi.
Low content of benzoic acid and/or sodium salt thereof as preservative is widely used in food and medicine manufacture field, its effective concentration as preservative is generally 0.1˜0.2% in an oral or external preparation[3], sodium benzoate as preservative generally has a concentration of 0.5% in a neutral or subacid pharmaceutical preparation[4]; tinctures or ointments comprising benzoic acid at a high concentration of 6˜12% are useful in the treatment of tinea of feet and hands[5]. However, neither compositions comprising benzoic acid and/or sodium salt thereof alone, especially benzoic acid and/or sodium salt thereof at a low content of 0.2% or below as active ingredient, nor the vaginal compositions comprising low content of benzoic acid and/or sodium salt thereof in combination with low content of other organic acid preservatives as active ingredients, are disclosed.
Propionic acid and/or a salt thereof, and sorbic acid and/or a salt thereof, as therapeutic agent, at a high concentration, are useful in alleviation of vaginal discomforts. U.S. FDA shows in Federal Register/Vol. 48, No. 199, 46704/Oct. 12, 1983/Proposed Rules that propionate (calcium salt or sodium salt) at a single dose of up to 2.3 g and a concentration of up to 20% is safe and effective in a vaginal preparation, and has an inhibition effect on fungi and Gram-positive cocci; in addition, another document shows that propionate sodium has a medicinal concentration of 5% in eye drops and a medicinal concentration of 5˜10% in anti-fungal solutions[6], the vaginal compositions comprising 0.5% or less propionic acid or a salt thereof as active ingredient are not disclosed.
Dehydroacetic acid is generally used as anti-tinea agent, and has a good inhibition effect on many pathogenic fungi at a concentration of from 0.05 to 0.5%[7]. However, it is not disclosed that dehydroacetic acid or a salt thereof at a concentration of less than 0.05% is applied to against the pathogenic fungi.
U.S. FDA shows in Federal Register/Vol. 48, No. 199, 46704/Oct. 13, 1983/Proposed Rules that vaginal lotions comprising 1˜3% potassium sorbate are regarded to be safe and effective. The vaginal compositions comprising 1%, or even 0.1% or less of sorbic acid or a salt thereof as active ingredient are not disclosed.
To sum up, there is no report on an antibacterial (bacteriostatic) composition comprising low content of benzoic acid and/or sodium salt thereof in combination with organic acid preservatives, such as low content of dehydroacetic acid and/or sodium salt thereof, and/or low content of propionic acid and/or a salt thereof, and/or low content of sorbic acid and/or a salt thereof, as active vaginal ingredients.